Baffle plate in a heat exchanger

ABSTRACT

A heat exchanger for a motor vehicle, has an outer sheath and heat exchanger tubes are arranged in the outer sheath and a medium is feedable into the sheath on the front side and is removable on the opposite side, wherein a front plate is arranged in each case on the end side of the covering, wherein the front plate has openings through which the medium is transferrable into the heat exchanger tubes, and, in particular, the heat exchanger tubes at least partially reach through the openings, which heat exchanger is characterized in that flat surfaces are formed on the front plate on the border side between the openings, wherein guide elements are arranged indirectly or directly in front of the flat surfaces in the direction of flow, wherein the face areas of the directing elements overlap at least the flat surfaces in the direction of flow.

The present invention relates to a heat exchanger according to the features in the preamble of patent claim 1.

It is known from the state-of-the-art to use heat exchangers in particular in motor vehicles in order to cool components by a medium and/or to withdraw heat from the medium in a targeted mariner. For example it is possible to cool the cooling water of an internal combustion engine of a motor vehicle in a targeted manner by a second medium in particular air. However, it is also possible to cool exhaust gas of the motor vehicle for example in order to resupply the cooled exhaust gas itself to the internal combustion process.

From DE 434 34 05 A1 for example a tube bundle heat exchanger is known at one end of which a medium is introduced, impacts a tube bottom and accumulates at the tube bottom and is then conducted through the heat exchanger tubes situated in the tube bottom. In accordance with the counter-flow principle, a second medium is introduced on the outside of a sheath of the heat exchanger, which second medium then flows through the heat exchanger and exits the heat exchanger again at an exit site located opposite the entry site of the second medium.

A disadvantage is that when using such a tube bundle heat exchanger as exhaust gas heat exchanger, in particular the tube bottom is at least locally exposed to high temperatures of the flowing exhaust gas.

An object of the present invention is to reduce the thermal effect of media flowing through a heat exchanger on the structural components in the heat exchanger.

According to the invention, the stated object is solved with a heat exchanger for a motor vehicle, in particular an exhaust gas heat exchanger, according to the features set forth in patent claim 1.

Advantageous embodiments of the present invention are the subject matter of the dependent patent claims.

The heat exchanger according to the invention for a motor vehicle is in particular configured as exhaust gas heat exchanger, wherein the heat exchanger has an outer sheath with heat exchanger tubes arranged in the outer sheath, and a medium can be introduced into the sheath at a front side of the sheath and can be discharged on the opposite side, wherein the medium then flows through the heat exchanger tubes. On each front side of the sheath a front plate is arranged wherein the front plate itself has openings and the medium, which flows through the openings into the heat exchanger tubes, first enters the heat exchanger tubes through the openings and at the front side exits again from the heat exchanger tubes through the openings. In particular the heat exchanger tubes traverse the openings at least in regions. According to the invention a heat exchanger is characterized in that even surfaces are formed at a border of the front plate between the openings, wherein guide elements are arranged in flow direction directly or indirectly before the even surfaces, wherein the face area of a guide element in flow direction covers at least one even surface.

Within the scope of the invention the term sheath means in particular an outer sheath, especially preferably a heat exchanger cartridge in which the heat exchanger tubes are in particular arranged as a tube bundle. The sheath can preferably be formed from a metallic material for example in the manner of a tube but also from metal sheets, wherein the sheath is then longitudinally seam welded. Within the scope of the invention the sheath is in particular made of a steel material, particularly preferably from a material that is resistant against the corrosive properties of the exhaust gases. Within the scope of the invention it is also possible however that the sheath is made of a lightweight metal material, for example aluminum or the like.

In the sheath itself the heat exchanger tubes are then arranged as a tube bundle, wherein the individual heat exchanger tubes are in particular held by a front plate, particularly preferably a respective front plate arranged in the region of a respective end of the sheath. The front plates themselves are also known as tube bottom or as tube bracket. For this purpose the front plates have recesses, wherein the heat exchanger tubes are either coupled with the recesses or extend at least partially, in particular completely, through the recesses. This makes it possible that a medium, which enters at a front side into the sheath and also exits the sheath again at the front side, initially impacts the front plate arranged at the entry side and then flows through the openings into the heat exchanger tubes. In particular this medium is an exhaust gas which is conducted through the heat exchanger tubes. However, within the scope of the invention any other medium in a fluid and/or gaseous state can be conducted through the heat exchanger.

On the front plate itself an elevated temperature, in particular in the form of heat accumulation, forms locally as a result of the medium impacting the front plate. The heat is then carried along or dissipated by the exhaust gas flowing through the heat exchanger tubes. However, those portions of the front plate configured as even surface are always exposed to the impacting exhaust gas flow and thus heat up significantly stronger, which in particular applies to the border region of the front plate because here the openings are not formed or are only formed partially in particular in the case of offset openings. This may result in thermal deformation of the front plate leading to leakages of the heat exchanger, in particular after several years of intensive use. On one hand this may be compensated by using higher-grade and particularly thick-walled front plates which however is associated with increased production costs. In contrast, the solution according to the invention provides to arrange corresponding guide elements in the direction of flow before the front plate either indirectly, i.e., at a distance, or directly, approximately directly or in direct contact with the front plate itself so that the flowing medium, in particular the flowing exhaust gas, is conducted by the guide elements in the direction of the center of the front plate and/or the openings in the heat exchanger tubes and does thus not impact the even or plane surfaces. This avoids increased heating of the even surfaces relative to the remaining front plate which in particular improves heat resistance and increases the service life of the heat exchanger while using conventional materials and optimized use of material, i.e., minimal wall thickness. This enables building a temperature resistant heat exchanger with longer service life without having to use higher-grade materials and/or more material.

Within the framework of the invention, the guide elements are in particular configured as bulges which protrude into the inner space of the heat exchanger. Within the scope of the invention, the guide elements can also be configured as embossment which protrudes into the inner space of the heat exchanger. Thus the guide elements rise from the inner sheath surface of the sheath and/or the flange in the form of a bulge, in the direction of the inner space of the heat exchanger. For this purpose, the guide elements have particularly preferably a tip which is enlarged in the direction of flow of the medium, in particular the face area of the respective guide element increases. Within the scope of the invention the face area increases in particular in a degressive course. This ensures on one hand that the tip, which protrudes in a direction opposite to the direction of flow of the medium, in particular the exhaust gas, has an optimal flow resistance with the subsequently increased face area of the guide element.

In particular the guide elements are configured at least partially in the form of a rocket tip and/or a water drop, in particular in a hybrid form of the aforementioned flow-optimized shapes. The guide elements can also have the shape of a conical cross section, an at least semi-conical cross section, a triangular prism but also a cubical cross section.

Within the scope of the invention it is also possible that the guide elements are inserted into the inflow funnel as a separate component. For example the guide elements are then coupled in an inner sheath surface of the inflow funnel by thermal joining, for example by a soldering or welding process. Within the scope of the invention it is also conceivable that multiple guide elements are formed on a guide element plate, for example by forming, and the guide element is then inserted into the inner space of the inflow funnel and is arranged in correspondence with the front plate situated in flow direction behind the guide element so that the even surfaces are not exposed to the hot exhaust gas flow and with this an increased heat production.

The guide elements are however configured so as to substantially extend from the border into the inner space, which is why the aforementioned examples have to be seen respectively halved. In particular a degressive increase of the face area means that the face area initially increases to a stronger degree and subsequently continues to increase but to a smaller degree.

In particular a rear side of the guide element viewed in flow direction is in this case configured to drop straight thus preventing a pull effect which may otherwise occur due to a surface that gradually approaches the inner sheath surface of the heat exchanger again. Otherwise the advantage important for the invention of the guidance of the flowing medium via the even surfaces could not be realized.

In particular multiple guide elements are arranged radially circumferentially spaced apart. A guide element is preferably always assigned to or arranged upstream of an even surface in the border region of the heat exchanger. The heat exchanger itself can for example have a square or rectangular cross section. Within the framework of the invention the heat exchanger may however also have a round and/or oval cross section, wherein in this case even surfaces remain in the border region of the front plate due to the openings.

Further preferably, the sheath of the heat exchanger is coupled with a flange. Within the scope of the invention the flange can also be a pipe socket, wherein in this case the flange of the pipe socket is coupled with the sheath. In particular the pipe socket is at least partially inserted into and/or pushed onto the sheath in flow direction. Within the scope of the invention the guide elements are then again particularly preferably arranged in the flange itself.

For a particular cost effective production the flange is in particular configured as cast part, wherein the guide elements are couple one-piece with and of the same material as the flange, and in particular when the flange is configured as cast part the guide elements are directly cast onto the flange or are coupled with the flange as external components. Preferably the guide elements are in this case welded into the flange and/or soldered with the flange. Within the scope of the invention it is also possible to integrate a further frame component which circumferentially extends outside on the inner sheath surface, wherein the guide elements are then formed in the frame component itself or are formed on the frame component.

Further within the scope of the invention the inner sheath surface of the flange and/or the surface of the guide elements is preferably coated. The coating is in particular a thermally resistant coating and/or a flow-optimized coating. This in particular increases the service life of the guide elements, while at the same time minimizing the counter pressure in the heat exchanger, caused in particular by the guide elements due to the flow-optimized surface.

Further advantages, features, properties and aspects of the present invention are the subject matter of the dependent claims. Preferred embodiments are shown in the schematic Figures. These are intended to facilitate understanding the invention. It is shown in:

FIGS. 1 a and b a perspective sectional view and a cross sectional view through a heat exchanger according to the invention,

FIG. 2 a longitudinal section through a heat exchanger according to the invention with inserted heat exchanger tube and

FIG. 3 a front view onto a heat exchanger with front plate.

In the Figures the same reference signs are used for the same or similar components even when a repeated description is not given for reasons of simplicity.

FIG. 1 a shows a heat exchanger 1 according to the invention in a perspective partial sectional view. The heat exchanger 1 has a sheath 2 with an inserted front plate 3. On one end 5 of the sheath 2 a flange 6 with inflow socket 6 a is provided. In the inflow socket 6 a itself the guide elements 9 are formed which, as will be explained in FIG. 1 b, are arranged in flow direction S of the fluid upstream of the even surfaces 8. The guide elements 9 can be formed one-piece with and of the same material as the inflow socket 6 a or fastened in the inflow socket 6 a as external components. Within the scope of the invention it is also possible that the guide elements 9 are formed on each side of the inflow socket 6 a by a guide plate or the entire guide plate is introduced into the inflow socket 6 a.

Further, the end 5 of the sheath 2 is configured enlarged so that here a circumferential lip 13 form fittingly receives at least a portion of the inflow socket 6 a. Further a connection socket 14 is arranged on the lip 13 which conducts a not further shown coolant in a coolant channel 15 according to FIG. 2, which is formed on a rear side of the front plate 3 and thus additionally cools the front plate 3. The lip 13 and the inflow socket 6 a are preferably coupled with each other in a materially bonding manner, in particular soldered or welded to each other.

FIG. 1 b shows a cross sectional view of a heat exchanger 1 according to the invention, wherein the heat exchanger 1 has a sheath 2 with inserted front plate 3, The front plate 3 itself has openings 4, wherein heat exchanger tubes not further shown in FIG. 1 can be inserted into the openings 4. Further shown is the flow direction S of a medium flowing through the heat exchanger 1. At the end 5 of the sheath 2 a flange 6 is arranged upstream of the sheath 2. The medium flows through the flange 6 in the direction of the sheath 2 and first impacts front plate 3. Herby the medium flows through the openings 4, wherein even surfaces 8 are arranged in the border region 7 of the front plate 3 itself. A guide element 9 is arranged in flow direction S upstream of the even surfaces 8. The guide element 9 itself has a tip 10, wherein the guide element 9 then increases in size starting from the tip 10 in flow direction S, in particular in the form of a bulge protruding into the inner space of the flange 6.

FIG. 2 shows the heat exchanger 1 in a longitudinal section, wherein the front plate 3 is arranged on the end of the sheath 2. Here the front plate 3 has an even surface 8 in the border region 7, wherein the front plate 3 itself is traversed by a heat exchanger tube 11 in the opening 4. The direction of flow S of the medium through the heat exchanger tube 11 is drawn in. The guide element 9 is arranged in flow direction S upstream of the front plate, wherein FIG. 2 illustrates that the flow direction S flows from a rear end 12 of the guide element in the direction toward the heat exchanger tube 11 and is thereby prevented from flowing onto the even surface 8 in the border region of the front plate 3. Further shown is a cooling channel 15, which conducts a not further shown coolant via the connection socket 14 to the rear side of the front plate 3 and to the tubes 16 which are partially arranged in the heat exchanger 1, and thus in particular cools the front plate 3. Further shown is a separating wall 17, which also contributes to delimiting the cooling channel 15. As shown here, the connection sockets 14 themselves can be form fittingly attached onto the lip 13, however they can also be configured one-piece with and of the same material as the lip 13. It can also be seen in FIG. 2 that the flow direction S, and with this exhaust gases flowing through the tubes 16, do not impact the even surface 8 where they would otherwise lead to an increased heat production, but are rather directly conducted into an inner space I of the tubes 16.

This can be recognized particularly well in FIG. 3, which shows that here the individual openings 4 are each offset in the front plate. In the border regions 7 the even surfaces 8 are formed, which however are covered by the respective guide elements 9 in flow direction S, which in FIG. 3 extends into the image plane. The guide elements 9 are schematically drawn in because they are positioned above the front plate 3 relative to the image plane. Thus the face area of the guide element 9 is greater than the even surface 8 of the border region of the front plate 3, which lies behind the guide element 9 relative to the image plane and is thus covered by the face area of the guide element 9. The exhaust gas flowing in the direction of the image plane with the inflowing medium is thus prevented from flowing onto, in particular from accumulating before, the surfaces 8 of the guide element 9, and is conducted into the openings 4 in a targeted manner.

REFERENCE SIGNS

-   1—heat exchanger -   2—sheath -   3—front plate -   4—opening of 3 -   5 end of 2 -   6—flange -   6 a—inflow socket -   7—border region -   8—even surface -   9—guide element -   10—tip of 9 -   11—heat exchanger tube -   12—rear end of 9 -   13—lip of 2 -   14—connection socket -   15—cooling channel -   16—tube -   17—separating wall -   S—direction of flow -   I—inner space 

What is claimed is: 1.-9. (canceled)
 10. A heat exchanger for a motor vehicle, in particular exhaust gas exchanger, comprising: an outer sheath; heat exchanger tubes arranged in the outer sheath, wherein a medium is introducible into the sheath at a front side of the outer sheath and is dischargeable on a another side of the outer sheath opposite the front side; a front plate arranged in the sheath at the front side of the outer sheath, said front plate having openings for passage of the medium into the heat exchanger tubes, said openings being configured as circular holes and are arranged offset to each other, and wherein even surfaces are formed between the openings at a border of the front plate; and guide elements arranged in flow direction of the medium directly or indirectly upstream of the even surfaces, wherein a face area of the guide elements covers in flow direction at least the even surfaces.
 11. The heat exchanger of claim 10, wherein the heat exchanger tubes at least partially traverse the openings.
 12. The heat exchanger of claim 10, wherein the guide elements are configured as bulge that protrudes into an inner space of the heat exchanger.
 13. The heat exchanger of claim 10, wherein the guide elements have a tip and increase in size in the flow direction.
 14. The heat exchanger of claim 13, wherein the face area of the guide elements increases in the flow direction.
 15. The heat exchanger of claim 14, wherein the face area increases degressively.
 16. The heat exchanger of claim 10, wherein the guide elements are arranged spaced apart along a circumference of the front plate.
 17. The heat exchanger of claim 10, further comprising a flange coupled with the sheath, wherein the guide elements are arranged in the flange
 18. The heat of claim 17, wherein the flange is configured as a cast part, and wherein the guide elements are configured one-piece with and of a same material as the flange or are coupled in the flange as external components.
 19. The heat exchanger of claim 17, wherein an inner sheath surface of the flange and/or a surface of the guide elements is coated with a coating
 20. The heat exchanger of claim 19, wherein the coating is at least one of a thermally resistant and a flow optimized coating. 